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Topic: Using oxygen for an air supply (Read 3481 times)

While at the gas engine show at Zolfo Springs Fla I met a man who also made castings. He stated that he used an oxygen bottle for an air supply rather than a blower. I thought this sounded inferior and expensive. But I always wondered how it worked. There was a time my blower had quit where I had a full pot of iron melted, but not hot enough to pour. So by the time I got another blower aranged, it had froze up. Most foundry men know that once the iron is cold, it would expand upon reheating, cracking the crucible . So I lost a new crucible. So I got this bright idea to try and have a backup air supply. So first I tried using air from my 5 hp compressor . It just did not have the air to even melt aluminum. So then I took my torch and arranged it in place of the blower. This I am sure could work, but not as I had it set up. Oxygen is too pure for an old set up. I think if you never used anything else, it would work.

Just thinking out loud but if you had molten iron and inserted an oxygen lance, wouldn't it self heat for a while a la a basic oxygen furnace? Of course it may reduce the carbon content...or make a hideous mess...

I was busy earlier and could not finish my writing. One thing that happened, as I see it , we have all seen the signs "no smoking oxygen in use". They say oxygen does not burn, but it can make a flame of a blade of grass. I burn propane and some times diesel fuel or kerosene . I looked down the blow pipe and it is mildly littered with bits and oily like black, like lamp black from a kerosene light . So what I surmise happened was when I packed my Victor torch handle in the end of the blow pipe where the blower was, and cranked the pressure to 80# the oxygen made all of those particles burn.It nearly blew my thumb off and was hard on my hearing. It did go out and there was a short build up of raw gas first . But I have been doing this since 1980. Something went boom more than ever. Look at what it did to the base block. Like dynamite it split it in 3 pieces and cracked the furnace all over. It never blew like that before. It must have filled up more raw gas without burning longer than I thought. But when it blew out the end of the pipe I was sure it the carbon buildup everywhere inside, as it blew out little burning bits and of white fire. Very hot. No I am not done till I light the sky up. I am going to make a short blow pipe and make sure that there is no carbon style half burnt fuel in it or on the furnace walls. The people at the welding shop always said that if you put oil in your torch and turn up the pressure it will ignite and blow you up. So maybe this is just not a good idea. Was just trying to run it with out electric was my interest . Blowing my furnace apart was a drawback I can deal with. And my hand is only a little sore. And I already do not hear well. Around a cupola if the spout freezes up they use a black steel pipe hooked directly to the oxygen regulator and lite it to burning by sticking it in the molten metal. The pipe burns like a torch and cuts through the cold metal. Yes I now think that the oxy would burn out the carbon in the iron. I think I will shelve this idea and build a gas engine powered blower . Don't look like I can add pictures today.

I have used mig welding gas mixture and nitrogen as cleaning air supply in electrical cabinets where it was unpractical to take a compressor. A small cylinder packed with 3000 PSI with a regulator goes a long way.

I am with John and Mike, please don't use oxygen other than the way you are properly trained to do it in welding or other processes where all the safety precautions are in place. Your gas engine powered blower is a really great idea.

It seems oxygen should be safe, as it is in the air all around us, we breathe it and we use it for medical etc. But all our ideas are based on the oxygen content of air, around 21%. The nitrogen that comes with it dilutes it, and gets in the way of oxygen atoms reaching the fuel atoms and so slows the whole process.

How many things can you think of that don't combine with oxygen in rusting or similar. Most things we think of as flammable need a match or even kindling to get them to light.

But even 2% enrichment of the oxygen in air changes everything. Things that don't burn in air, burn when there is more oxygen concentration. Things that burn, burn more fiercely. Things that need kindling in air, only need a match, and things that only need a match, only need to have that extra oxygen. Like those specks of carbon.

With enough oxygen, even the oil in a fingerprint is enough to cause a fire that melts the steel where the fingerprint was, if you are lucky. Of not, the steel starts to burn! And the concrete it was standing on.

I was only involved with one oxygen compressor, but it gave me an introduction to the issues. It had to be assembled and all maintenance had to be done in a special oil free room by workers wearing special gloves, so no fingerprints. I asked the Manufacturer for a recommendation on fire protection and extinguishers to be provided around the machine.

The answer was two points. First, don't be there if it happens. Second, look out the drawings for the foundations so you can pour new ones while we build a new compressor, there is nothing to clean up first.

Admittedly we were dealing with something near 90% oxygen! But all the standards required some precautions for all concentrations above 2% above the concentration in standard air. With more precautions required for higher concentrations. Fortunately we never found out if they were correct in all the detail, but there is no doubt about the first point.

When I first posted, my thoughts were to advise people this is a bad idea. Although I am still intrigued by it I do not intend to work at it at this time with out more information. I am concluding now I would need a more scientific apparatus to use oxygen opposed to a blower. I think now I also had the air pressure way too high. If one were to use oxy then it would maybe take less pressure or a mixing valve so it comes out mixed, like a copper tip not carbon steel, as a welding torch uses copper to cut steel. Since I weld and cut with it, it must scientifically speaking, work. Or possibly employ the use of nitrogen to calm it down . It may do to just turn down the pressure. But do to the contamination of combustibles and the voliticity of pure oxygen I would think scientifically if an unregulated mixture entered the furnace it could eventually start burning the carbon in the iron making a huge mess. For sure it was a bad idea to put a mere 80# into the blow tube especially with the fire already burning in the furnace.

I have heard (not seen) that when the insides of a cutting torch begin burning the flame can eat through and come out the side of the torch. It does not have to use the customary opening. It makes it's own.

When the torch starts burning through it is from a buildup of carbon inside. Once it burns just a little bit inside, more carbon builds up from having burned. So the fire makes fuel for itself . Interesting how a drop of oil on a valve could be so destructive. A fingerprint burning is even crazier. I would think the mixer and tip would need to be back out of and away from the inside of the furnace. Just a blast going through a port.

I remember working with a millwright crew back in the early 80’s and we drilled and tapped a lot of base plates for pumps and motors with a mag based drill. Rapid Tap was the preferred cutting oil and was used in way too much excess. We would have a bit of fun with the new guys by blowing out the chips with a blast of oxygen from a oxy/acetylene torch as a kaboom and flames always followed . But I also remember the time one of the guys in the shop capped off one end of a 20’ stick of 6” pipe with a ziplock baggie and the proceeded to fill in the acetylene: when he struck his striker at the open end: 😯 the blast was horrendous, but, because the ziplock held no pressure, it was all concussion .

My neighbor worked in a welding shop. Usually around the 4th of July he would light the torch and set a large welding flame. Then he would snuff it out and dunk the tip in water to cool it. Then fill a balloon . Then tieing it to 3 more filled with helium and a 20' tail of rag soaked in diesel. He lit it and it would drift out over the ball field and kaboom. Very loud . Once they put one in the city sewer and it set it on fire with flames coming out of the grates along the street. Basically it is the same as a carbide cannon. I always thought static electricity would set it off. He always was a nut.